Washing apparatus

ABSTRACT

731,014. Purifying liquids; gravity-separation apparatus. NITROGLYCERIN AKTIEBOLAGET. April 28, 1953 [April 29, 1952], No. 11664/53. Class 46. The apparatus shown is for washing a liquid such as a nitrated product with another liquid immiscible with it and having a different specific gravity. Washing liquid, such as water, to which an alkali has been added, introduced at 5, and nitroglycerine introduced at 4 are mixed in an injector 3 with the help of compressed air introduced at 6. The mixture passes into a chamber 1 where the air maintains vigorous movement before discharge at 9. The liquid mixture passes between plates 7 forming an angle of between 45 degrees and 60 degrees with the horizontal and spaced apart by a distance small (e.g. 5 mm.) compared with their extent into an intermediate compartment 8 and thence through openings 12 in a wall 10 into a separating chamber 11. From the latter the washing liquid overflows at 16 and the nitroglycerine at 15. The lower end of the separating chamber 11 communicates with an inspection glass 13 ; a layer h e of mixed liquids separating the two liquids may be maintained at the level of this glass by adjusting the height H between the overflow levels 15 and 16, for example with interchangeable nozzles.

WASHING APPARATUS Filed March 12, 1953 ,Z/Wm/ra? A as Aw: Fiery A/assa/v WASHING APPARATUS Nils Agne Percy Nilsson, Gyttorp, Sweden, assignor to Nitroglycerin Aktiebolaget, Gyttorp, Sweden, a corporation of Sweden Application March 12, 1953, Serial No. 341,990

Claims priority, application Sweden April 29, 1952 6 Claims. (Cl. 260-467) This invention relates to an apparatus for washing liquid substances or products and/or finely divided solid substances, such as nitrated or similar products, for example nitroglycerin or nitroglycol, with a Washing fluid having a specific weight different from that of the product to be washed and being non-miscible with .the latter, or only miscible therewith to an insignificant extent.

The chief object of the invention is to provide an apparatus for a washing of this kind in which the washing fluid and the product can be rapidly separated from each other after washing. A further object of the invention is to provide a washing apparatus adapted to be combined with a mixing apparatus, preferably of the injector type, in which the product to be washed and the washing fluid are intimately mixed with one another by means of a com pressed gas, for example air, before introduction into the washing apparatus where the gas is allowed or caused to pass oif and escape from the liquid mixture prior to the separation of the latter in difl'erent layers.

In accordance with the foregoing the washing apparatus according to the invention comprises a compartment or chamber which is provided at the bottom with an inlet connected to a mixing apparatus of the kind described for receiving therefrom the mixture of the product to be washed, washing fluid and compressed gas, as indicated above, the said chamber being also provided with a gas outlet at the top to allow the escape of gas separated from the mixture in the chamber. At least on one side the chamber is bounded with a series of substantially parallel plates located above one another and separated by a small intermediate space, suitably within the ranges 2 to mm, preferably 3 to 7 mm, so as to secure a substantially laminar flow of the liquid mixture between the plates which are arranged sloping outwards and downwards from the chamber towards an adjacent compartment. In the lower part of said compartment is arranged one or more outlets to a separating chamber in which the washed product and a washing fluid are separated from one another by forming different layers, owing to their different specific weights.

In this connection it should be pointed out that the term liquid substances or products to be subjected to washing according to the invention, refers both to substances or products which are themselves in a liquid state of aggregation at normal temperature and also to solutions of liquid or solid substances. in both cases it is, of course, a condition that the substances in question or the solvent or the solution are non-miscible with or nonsoluble in the washing fluid, e. g. water, or only to an insignificant extent. Further, as indicated above, the apparatus may also be applied for washing finely divided solid substances which are suspended in the washing fluid with the help of compressed gas in which case the washed product is separated from the fluid after washing by deposition.

A form of construction for the apparatus according to the invention is shown diagrammatically in vertical section in the accompanying drawing and the invention is atent 2,755,302 Patented July 17, 1956 described in connection therewith as applied to the washing of nitroglycerin.

In the drawing 1 is a washing chamber or zone of relatively great height in proportion to its horizontal sectional area. At the bottom this chamber is provided with an inlet 2 to which an injector 3 is connected for injecting crude nitroglycerin and a washing fluid, such as water to which an alkali has been added, with the help of compressed air, the said fluids being supplied to the injector 3 through conduits 4, 5 and 6, respectively. The lower part of the chamber is fitted with tight walls, while the upper part is bounded on one side by a series of plates or separating surfaces 7 located above one another, all of which are substantially parallel and slope outwards and downwards from the chamber 1 towards the adjacent compartment 8. The plates 7 form an angle of between 45 and 60 with the horizontal plane, and they lie so close to one another that the mixture of nitroglycerin and washing fluid running down between them will have a quiescent substantially laminar flow. A suitable distance between the plates is about 5 mm. In comparison with the space between them, the plates 7 have an essential extention in the direction from the chamber 1 towards the compartment 8, and they are preferably so arranged above one another that the free cross-sectional area in the chamber 1 substantially decreases progressively towards the upper end of the chamber where the gas outlet 9 is arranged.

The compartment 8 into which the disc-shaped flow passages between the plates 7 open, is separated by means of a vertical wall 10 from the separating chamber or zone .11 with which the compartment 8 communicates through openings 12 formed in the lower part of the separating wall 10. The separating chamber 11 at its lower end is provided with a vertical inspection glass 13 which is connected at its lower end to a bent 'U-shaped tube 14 the other limb of which is connected to an'overflow basin 15 provided with an overflow pipe. The separating chamber 11 is also fitted at the top with an overflow pipe 16 but it is otherwise closed at its upper end.

The apparatus works as follows:

The washing fluid and nitroglycerin are mixed with the help of compressed air in the injector 3 and are injected from the latter into the inlet 2 in the washing chamber 1 where the air passes oif and escapes through the gas outlet 9 while keeping the liquid mixture in vigorous movement in the chamber during its passage upwards. The liquid mixture runs off continuously between the plates 7 where all turbulence in the mixture is caused to cease in consequence of the fact that only a laminar flow is possible between the plates. If any tendency towards and eddying movement is still exhibited in the liquid mixture, this is clamped down further before the mixture enters the separating chamber 11 by the reduced passage through the openings 12 in the intermediate wall 10. Owing to the practically complete absence of turbulence in the separating chamber 11 and its lower extension in the form of the inspection glass 13, the washing fluid will collect above the nitroglycerin. However, owing to the fact that the separation requires a certain time to take place, a separation layer of the height he will be formed between the two liquids which layer, in view of the fact that the separating chamber 11, the inspection glass 13 and the bent tube 14 are so dimensioned that they form a U-tube or two receptacles communicating at the bottom, can be maintained at the level of the inspection glass 13. The bent tube 14 will thereby be filled with nitroglycerin which runs olf progressively from the overflow basin 15 but always works in the equilibrium system with the height hn. On the other hand, the washing fluid is separated off and fills the upper part of the separating chamber to a height of hv which is determined by the overflow pipe 16. The difference in height between the level in the overflow basin 15 3 and the overflow level in the separating chamber 11 is denoted by H and if the specific weight of the washing fluid is denoted by sv and the specific weight of the washed product (nitroglycerin) by Sn, it is obvious that the following conditions of equilibrium will exist:

Thus, when the specific weights and the rate of separation on which the height he of the separation layer depends are known, it is obviously possible to bring the last-mentioned layer into the desired position, by adjusting the height H between the overflow levels in the basin 15 and the chamber 11, which may be done, for example, with the help of interchangeable nozzles.

According to the character of the washed product, the apparatus can be equipped with cooling or heating devices in the form of spiral coils for a suitable medium, built into the apparatus, for example.

The apparatus may also be adapted to the requirements in some other manner by changing the form, size and internal arrangement of the parts without departing from the scope of the invention.

I claim:

1. An apparatus for separating a mixture of two immiscible liquids, one of which has a higher specific gravity than the other, into its components, which comprises in combination a washing chamber and an adjacent interconnected separating chamber having heights greater than their widths, means at the bottom of said washing chamber for introducing into the chamber a fluid mixture comprising said immiscible liquids and an inert gas, the chamber being provided with an outlet for the gas at its top, a plurality of superposed spaced-parallel plates mounted in the washing chamber, said plates sloping downwardly towards said separating chamber, being spaced so closely that the liquid passes therebetween in laminar flow thereby causing quiescence and partial separation of the liquids and being so constructed and arranged that the liquid mixture is forced to pass between said plates on its way into said separating chamber, means for removing the lighter of said liquids from the upper part of said separating chamber and means for withdrawing the heavier liquid from the bottom of said separating chamber while holding it at a predetermined level.

2. The apparatus of claim 1 wherein the spaced-parallel plates slope at an angle of from about 45 to 60 to the horizontal. I

3. The apparatus of claim 1 wherein the means for withdrawing the heavier liquid comprises a U-shaped conduit one end of which is connected to the bottom of said separating chamber while the other end is connected to an adjustable overflow device adapted to maintain a constant level of the heavier liquid in the separating chamber.

4. The apparatus of claim 3 wherein an inspection glass is provided at the bottom of the separating chamber to observe the level of the heavier liquid.

5. The apparatus of claim 1 wherein the means for introducing the liquid and gas mixture at the bottom of the mixing chamber comprises an air injector to produce mixing of the two liquids with the air.

6. In the washing of crude nitro compounds selected from the class consisting of nitro-glycerin and nitroglycol,

, the process which comprises mixing such a crude nitro compound with wash Water and air, passing this mixture into the bottom of a washing zone having a height which is greater than its diameter, passing the mixture upwardly in said zone in turbulent flow and then in quiescent laminar flow between a plurality of closely-spaced downwardly sloping separating surfaces, thereby causing at least partial separation of the nitro compound and the wash Water, passing the resulting mixture into a quiescent separating zone to produce further separation, withdrawing wash water from the top of said separating zone and withdrawing the nitro compound from the bottom of said separating zone at a rate maintaining a substantially constant level of the nitro compound in said zone.

References Cited in the file of this patent UNITED STATES PATENTS 952,222 Towne Mar. 15, 1910 1,076,666 Dorr Oct. 28, 1913 1,939,634 Schmid Dec. 12, 1933 

1. AN APPARATUS FOR SEPARATING A MIXTURE OF TWO IMMISCIBLE LIQUIDS, ONE OF WHICH HAS A HIGHER SPECIFIC GRAVITY THAN THE OTHER, INTO ITS COMPONENTS, WHICH COMPRISES IN COMBINATION A WASHING CHAMBER AND AN ADJACENT INTERCONNECTED SEPARATION CHAMBER HAVING HEIGHTS GREATER THAN THEIR WIDTHS, MEANS AT THE BOTTOM OF SAID WASHING CHAMBER FOR INTRODUCING INTO THE CHAMBER A FLUID MIXTURE COMPRISING SAID IMMISCIBLE LIQUIDS AND AN INERT GAS, THE CHAMBER BEING PROVIDED WITH AN OUTLET FOR THE GAS AT ITS TOP, A PLURALITY OF SUPERPOSED SPACED-PARALLEL PLATES MOUNTED IN THE WASHING CHAMBER, SAID PLATES SLOPING DOWNWARDLY TOWARDS SAID SEPARATING CHAMBER, BEING SPACED SO CLOSELY THAT THE LIQUID PASSES THEREBETWEEN IN LAMINAR FLOW THEREBY CAUSING QUIESCENCE AND PARTIAL SEPARATION OF THE LIQUIDS AND BEING SO CONSTRUCTED AND ARRANGED THAT THE LIQUID MIXTURE IS FORCED TO PASS BETWEEN SAID PLATES ON ITS WAY INTO SAID SEPARATING CHAMBER, MEANS FOR REMOVING THE LIGHTER OF SAID LIQUIDS FROM THE UPPER PART OF SAID SEPARATING CHAMBER AND MEANS FOR WITHDRAWING THE HEAVIER LIQUID FROM THE BOTTOM OF SAID SEPARATING CHAMBER WHILE HOLDING IT AT A PREDETERMINED LEVEL.
 6. IN THE WASHINGS OF CRUDE NITRO COMPOUNDS SELECTED FROM THE CLASS CONSISTING OF NITRO-GLYCERIN AND NITROGLYCOL, THE PROCESS WHICH COMPRISES MIXING SUCH A CRUDE NITRO COMPOUND WITH WASH COMPRISES MIXING SUCH A CRUDE NITRO INTO BOTTOM OF A WASHING ZONE HAVING A HEIGHT WHICH IS GREATER THAN ITS DIAMETER, PASSING THE MIXTURE UPWARDLY IN SAID ZONE IN TURBULENT FLOW AND THEN IN QUIESCENT LAMINAR FLOW BETWEEN A PLURALITY OF CLOSELY-SPACED DOWNWARDLY SLOPING SEPARATING SURFACES, THEREBY CAUSING AT LEAST PARTIAL SEPARATION OF THE NITRO COMPOUND AND THE WASH WATER, PASSING THE RESULTING MIXTURE INTO A QUIESCENT SEPARATING ZONE TO PRRODUCE FURTHER SEPARATION, WITHDRAWING WASH WATER FROM THE TOP OF SAID SEPARATING ZONE AND WITHDRAWING THE NITRO COMPOUND FROM THE BOTTOM OF SAID SEPARATING ZONE AT A RATE MAINTAINING A SUBSTANTIALLY CONSTANT LEVEL OF THE NITRO COMPOUND IN SAID ZONE. 